The present invention relates to flexible shaft attachments used with rotary power tools accommodating bits such as small drills, sanders, polishers, grinders, engravers, saws and the like, and specifically to a handset for such a tool which is disposed at a working end of the flexible shaft.
Flexible power transmission shafts are known for use in driving tethered handpieces that are connected to rotary power tools. Through the connection to the flexible shaft, such handsets provide a user with enhanced maneuverability and facilitate manipulation of the working end of the tool. The user can more easily access difficult-to-reach or delicate workpieces to perform drilling, sanding, grinding, polishing, cutting, engraving or similar operations.
One drawback of conventional handpieces is that they are configured for receiving only the bit or working attachment. Thus, while providing finger-tip control, a disadvantage of this arrangement is that operations which require precise or straight-line movement of the tool are difficult to satisfactorily perform, due to the normal instability of hand-held units. Conventional handpieces lack fittings or formations for receiving guide attachments for maintaining the position of the handpiece relative to the workpiece.
Another drawback of conventional handpieces occurs when locking the bit or working attachment to the handpiece. Typically, a collet nut is used to clamp the shaft of the bit in a socket at the end of the flexible drive shaft. The collet nut is threaded upon the drive shaft end. However, since the flexible drive shaft is rotatable within its sheath, it is difficult to lock the collet nut in place to withstand the high speed rotation and vibration of the rotary tool. To address this problem, conventional handpieces employ a locking aperture in the handpiece which is in registry with a throughbore near the end of the flexible drive shaft. A thin elongate rod, such as a shaft of a bit, must be inserted through the locking aperture and into the throughbore to prevent the drive shaft from rotating relative to the handpiece. This operation is awkward and time consuming to perform.
Thus, a first object of the present invention is to provide an improved handpiece for a rotary tool flexible shaft attachment which features the ability to receive supplemental attachments such as guides, in addition to the conventional bits or working attachments.
Another object of the present invention is to provide an improved handpiece for a rotary tool flexible shaft attachment which features an easily actuable shaft lock for facilitating the attachment and removal of bits.
The above-listed objects are met or exceeded by the present rotary tool flex shaft with a handpiece featuring a working end of the housing which is configured for receiving supplemental attachments such as guides, in addition to the working attachment or bit. Another feature of the present handpiece is a built-in locking button which is easily actuated by the user with the same hand used to hold the handpiece. Thus, the other hand can be used to easily remove and replace the working attachment, which will be securely locked to the flexible shaft.
More specifically, the present invention provides a handpiece for a rotary tool including a flexible power transmission shaft configured for connection at one end to the rotary tool, and at the other end to the handpiece, with at least one locking formation affixed to the shaft. The handpiece includes a housing having a first end for receiving the shaft, and a second end configured for accommodating a working attachment, the housing defining a central throughbore for rotatably receiving the shaft. At least one locking actuator is disposed in the housing for releasable engagement with the locking formation, the handpiece is provided with a biasing force for biasing the actuator out of engagement with the locking formation, so that a preferably radially-directed user-applied force on the actuator overcomes the biasing force to enable locking engagement between the actuator and the locking formation. A working end of the handpiece housing is also configured for receiving supplemental attachments.
In another embodiment, a handpiece for a rotary tool includes a flexible power transmission shaft configured for connection at one end to the rotary tool, and at the other end to the handpiece. The handpiece includes a housing having a first end for receiving the power transmission shaft, and a second end configured for accommodating a working attachment. The housing defines a central throughbore for rotatably receiving at least a portion of the flexible shaft. An attachment formation located at the second end is configured for receiving an endcap, the endcap is configured for engagement upon the attachment formation, and preferably has a flared outer end. The endcap is removable to provide a location for accommodating supplemental attachments such as guides.